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Event Information

Monster Seminar JAM - Acid Rain: An Unfinished Environmental Problem

Presentator(s):

Dr. Gene E. Likens, Institute of Ecosystem Studies

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Abstract

Acid rain is a serious environmental problem affecting large regions of the Earth. Large areas of North America, Europe and Asia, as well as parts of the Southern Hemisphere, receive wet deposition that is 10 to more than 30 times more acid than would be expected from an unpolluted atmosphere. Acid rain was first observed in North America at the Hubbard Brook Experimental Forest in the White Mountains of New Hampshire (Likens et al. 1972). Studies of precipitation and streamwater chemistry have been done there since 1963, comprising the longest, continuous record of this type in the world. Federal legislation in the United States, the1990 Clean Air Act Amendments, directly addressed the acid rain problem in the U.S. for the first time.
Large amounts of calcium, an important plant nutrient, and other base cations have been depleted from forest ecosystems in the northeastern United States during the past 50 years by acid rain. As a result of the depletion of calcium, ecosystems within the Hubbard Brook Experimental Forest are much more sensitive to continuing inputs of strong acids in atmospheric deposition than expected based on long-term patterns of sulfur biogeochemistry alone. Depletion of calcium from the ecosystem has long-term implications for forest growth, as well as for changes in stream ecosystems and downstream lakes within the landscape. A watershed-ecosystem experiment was initiated in 1999 in the Hubbard Brook Experimental Forest to test the role of added CaSiO3 to a calcium-depauperated landscape.